The proposed research is designed to study the interaction between specific pharmacological agents and relaxation therapy in the treatment of hypertension. For this disorder, commonly prescribed pharmacological treatments are beta-blocking agents and diuretics. Relaxation therapy is a behavioral treatment which may have value as an adjunct. The proposed study will compare the effect of relaxation therapy added to either chlorthalidone, a diuretic, or atenolol, a beta-blocking agent. Correlations will be determined between the responses to certain pretests, such as stress tests, blood pressure variability and plasma renin, and response to relaxation and drugs. Fifty subjects will go through each of the following experimental phases: placebo (4 weeks), placebo plus relaxation (8 weeks), drug I (chlorthalidone or atenolol, 6 weeks), drug I plus relaxation (6 weeks), drug II (atenolol or chlorthalidone, 6 weeks), drug II plus relaxation (6 weeks). The order of pharmacological regimens will be counterbalanced across subjects. Dependent variables include blood pressure obtained at the laboratory, at the clinic, and during ambulatory monitoring. The results of the study may provide guidelines for the clinical management of hypertension in a biobehavioral framework. Specifically, it will provide data on whether the effect of relaxation added to two different commonly prescribed pharmacological agents will be additive or non-contributory. In addition, the results may expand our knowledge of the mechanisms of relaxation therapy with hypertension.